Well, proper dosage appears to be the key. They hide well but must have a great sense of smell. I dropped a half wafer on each side of the tank and within minutes I saw them pop out of the sponge “walls” (the dual HMF). I have some glutaraldehyde left over from my Planted tank days, so I spot treated the ones I could see.
Two days ago I saw 1 or 2. Yesterday I saw none. I’m going to add a little a food this morning and see what shows up.